1. Field of the Invention
The present invention relates to a gate valve for opening and closing a variety of openings, for example, relates to a gate valve capable of airtightly opening and closing an opening of a vacuum process chamber used for a production process of a semiconductor apparatus.
2. Description of the Related Art
In a dry etching step, a sputtering step or an epitaxial wafer forming step, etc. in the manufacturing process of a semiconductor device, a multi-chamber structure vacuum process apparatus comprising a plurality of vacuum process chambers connected with each other is used.
In a vacuum process apparatus of this kind, a wafer is transported to and from a transport chamber to a vacuum process chamber via a gate, and a gate valve is provided for securing a vacuum and cleanness of the vacuum process chamber. As a conventional gate valve, one disclosed in the U.S. Pat. No. 5,415,376 is known.
However, the conventional gate valve has disadvantages below.
First of all, the gate valve described in the above U.S. Pat. No. 5,415,376 is configured to guide a vertical move of a valve rod by a guide mechanism comprised of a pivotal shaft and a groove guide, so a certain clearance would be necessarily designed between the pivotal shaft and the groove guide. Due to this essential clearance, it is liable that the valve rod rattles and which becomes a cause of fluctuation and noise or ends up in causing rocking. This disadvantage becomes noticeable particularly when the gate valve is driven at a high speed.
Also, the one disclosed in the above U.S. Pat. No. 5,415,376 is a gate valve of a vertical drive type wherein the valve rod moves in the vertical direction, while in a gate valve of a horizontal drive type wherein the valve rod moves back and forth in the horizontal direction, since the gravitation of the valve body attached at one end of the valve rod acts as a moment on the horizontal drive of the valve rod, probability of an occurrence of fluctuation, noise and rocking due to the above rattling becomes higher.
The second disadvantage of the gate valve in the above U.S. Pat. No. 5,415,376 relates to a mechanism of making the valve rod move in an inclining way when the valve body opens and closes the opening of the vacuum process chamber. Namely, in the gate valve of the above U.S. Pat. No. 5,415,376, the valve rod is moved in an inclining way by spring action of a tension spring, however, when using the tension spring, a point contact at fixed portions at both ends becomes inevitable, so stress intensifies to the points and the fixed portion of the spring is liable to be damaged due to fatigue.
An object of the present invention is to provide a gate valve capable of not making any noise and preventing rocking even when driven at a high speed and having an excellent durability.
[1] To attain the above object, according to a first aspect of the present invention, there is provided a gate valve comprising a valve body (2) capable of opening and closing an opening of a sealed chamber, and capable of sealing the opening by inclination with respect to the opening; a valve rod (6) to one end portion of which said valve body is fixed, held so that it can move in a straight-move direction for the valve body to open and close the opening, and held so that it can incline about an inclination axis (41a); a regulation means (12) for regulating a straight movement in the direction of closing the opening of the valve body at a close position where the valve body closes the opening; a cam mechanism (31) connected to the other end portion of the valve rod outside the sealed chamber, for moving the valve rod straight by a supplied straight-move force, converting the supplied straight-move force to an inclination force and inclining about the inclination axis the valve rod wherein a straight movement is regulated at the close position toward the direction that the valve body seals the opening; and a drive means (60) for supplying the straight-move force to the cam mechanism; and wherein the valve rod is held so that it can move in a straight-move direction of opening and closing the opening via a pair of linear guides (48, 48) provided on both sides of the valve rod.
In the gate valve of the present invention, since a valve rod can be moved in a straight-move direction in a state of holding both ends of the valve rod by using a pair of linear guides, a conventionally required clearance disappears, consequently, it can attain silence even when the gate valve is driven at a high speed and rocking of the valve rod can be also prevented.
Note that in the above invention, the above linear guide (48) may be configured to have a guide body (44) being attached on the valve rod side, a guide rail (45) attached on the drive means side, and a rolling bearing (46) provided between the guide body and the guide rail.
Also, in the above invention, a inclination axis (41a) of the valve rod may be set on or near a straight line connecting to attaching portions of guide bodies of the pair of linear guides and the valve rod.
Furthermore, in the above invention, the inclination axis (41a) of the valve rod may be set on an axis line of the valve rod.
Also, in the above invention, a thrust bearing (42) can be provided at an attaching portion of the valve rod and the guide body of the linear guide.
Also, in the above invention, the valve rod (6) may be configured to be held by sandwiching by receiving a preload in the inclination axis (41a) direction from the pair of linear guides (48, 48).
Furthermore, in the above invention, a sealing means (10) for sealing between the valve rod and the airtight chamber may be further provided so that the valve rod can move.
Also, in the above invention, the thrust bearing may be attached to the guide body by a bearing holding member (43) and the bearing holding member may be shaped to be received in a concave portion (12a) formed on a stopper member.
[2] To attain the above object, according to a second aspect of the present invention, there is provided a gate valve comprising a valve body (2) capable of opening and closing an opening of a sealed chamber, and capable of sealing the opening by inclination with respect to the opening; a valve rod (6) to one end portion of which the valve body is fixed, held so that it can move in a straight-move direction for the valve body to open and close the opening, and held so that it can incline about an inclination axis (41a); a regulation means (12) for regulating a straight movement in the direction of closing the opening of the valve body at a close position where the valve body closes the opening; a cam mechanism (31) connected to the other end portion of the valve rod outside the sealed chamber, for moving the valve rod straight by a supplied straight-move force, converting the supplied straight-move force to an inclination force and inclining about the inclination axis the valve rod wherein a straight movement is regulated at the close position toward the direction that the valve body seals the opening; and a drive means (60) for supplying the straight-move force to the cam mechanism; and wherein the cam mechanism (31) comprises a rolling body (35); a rolling body holding member (38) for holding the rolling body and being driven by the drive means a cam member (32) arranged facing to the rolling body holding member, provided with a cam plane for the rolling body to roll thereon to incline the valve rod, and connected to the valve rod; and further comprising a compression coil spring (80) for maintaining a relative positional relationship of the rolling body holding member and the cam member constant while elastically permitting a change of a relative position of the rolling body holding member and the cam member.
In the gate valve of the present invention, since a compression coil spring is used in a cam mechanism to incline the valve rod, the spring can contact the valve rod which relatively inclines and the gate valve fixed side by a plane. As a result, it is possible to provide a gate valve capable of dispersing the elastic stress imposed on the contact portion of the spring and preventing breaks due to fatigue as a result of repeated drive, and having excellent durability.
Note that in the above invention, the compression coil spring (80) may be configured to be attached in a non-load state to an offset state so that a reactive force by the offset acts to recover the valve (2) to an initial position direction via a relative move of the rotation body holding member (38) and the cam (32).
Also, in the above invention, the compression coil spring (80) may be provided so as to surround the rotation body holding member (38) and the cam (32).
Furthermore, in the above invention, the rotation body (35) may be configured to comprise a roller (35a) having a rotation plane contacting the cam surface and a roller shaft (35b) for rotatably supporting the roller rotatably and being supported by the rotation body holding member.
Also, in the above invention, a sealing means (10) for sealing between the valve rod and the airtight chamber so that the valve rod can move may be further provided.